public
class
Thread
extends Object
implements
Runnable
| java.lang.Object | |
| ↳ | java.lang.Thread |
 Known Direct Subclasses
|
A thread is a thread of execution in a program. The Java Virtual Machine allows an application to have multiple threads of execution running concurrently.
Every thread has a priority. Threads with higher priority are
executed in preference to threads with lower priority. Each thread
may or may not also be marked as a daemon. When code running in
some thread creates a new Thread object, the new
thread has its priority initially set equal to the priority of the
creating thread, and is a daemon thread if and only if the
creating thread is a daemon.
When a Java Virtual Machine starts up, there is usually a single
non-daemon thread (which typically calls the method named
main of some designated class). The Java Virtual
Machine continues to execute threads until either of the following
occurs:
Developers
exit method of class Runtime has been
called and the security manager has permitted the exit operation
to take place.
run method or by
throwing an exception that propagates beyond the run
method.
There are two ways to create a new thread of execution. One is to
declare a class to be a subclass of Thread. This
subclass should override the run method of class
Thread. An instance of the subclass can then be
allocated and started. For example, a thread that computes primes
larger than a stated value could be written as follows:
class PrimeThread extends Thread {
long minPrime;
PrimeThread(long minPrime) {
this.minPrime = minPrime;
}
public void run() {
// compute primes larger than minPrime
. . .
}
}
The following code would then create a thread and start it running:
PrimeThread p = new PrimeThread(143);
p.start();
The other way to create a thread is to declare a class that
implements the Runnable interface. That class then
implements the run method. An instance of the class can
then be allocated, passed as an argument when creating
Thread, and started. The same example in this other
style looks like the following:
class PrimeRun implements Runnable {
long minPrime;
PrimeRun(long minPrime) {
this.minPrime = minPrime;
}
public void run() {
// compute primes larger than minPrime
. . .
}
}
The following code would then create a thread and start it running:
PrimeRun p = new PrimeRun(143);
new Thread(p).start();
Every thread has a name for identification purposes. More than one thread may have the same name. If a name is not specified when a thread is created, a new name is generated for it.
Unless otherwise noted, passing a null argument to a constructor
or method in this class will cause a NullPointerException to be
thrown.
Nested classes | |
|---|---|
enum |
Thread.State
A thread state. |
interface |
Thread.UncaughtExceptionHandler
Interface for handlers invoked when a Thread abruptly terminates due to an uncaught exception. |
Constants | |
|---|---|
int |
MAX_PRIORITY
The maximum priority that a thread can have. |
int |
MIN_PRIORITY
The minimum priority that a thread can have. |
int |
NORM_PRIORITY
The default priority that is assigned to a thread. |
Public constructors | |
|---|---|
Thread()
Allocates a new |
|
Thread(Runnable target)
Allocates a new |
|
Thread(ThreadGroup group, Runnable target)
Allocates a new |
|
Thread(String name)
Allocates a new |
|
Thread(ThreadGroup group, String name)
Allocates a new |
|
Thread(Runnable target, String name)
Allocates a new |
|
Thread(ThreadGroup group, Runnable target, String name)
Allocates a new |
|
Thread(ThreadGroup group, Runnable target, String name, long stackSize)
Allocates a new |
|
Public methods | |
|---|---|
static
int
|
activeCount()
Returns an estimate of the number of active threads in the current thread's thread group and its subgroups. |
final
void
|
checkAccess()
Determines if the currently running thread has permission to modify this thread. |
int
|
countStackFrames()
This method was deprecated
in API level 1.
The definition of this call depends on |
static
Thread
|
currentThread()
Returns a reference to the currently executing thread object. |
void
|
destroy()
This method was deprecated
in API level 1.
This method was originally designed to destroy this
thread without any cleanup. Any monitors it held would have
remained locked. However, the method was never implemented.
If if were to be implemented, it would be deadlock-prone in
much the manner of |
static
void
|
dumpStack()
Prints a stack trace of the current thread to the standard error stream. |
static
int
|
enumerate(Thread[] tarray)
Copies into the specified array every active thread in the current thread's thread group and its subgroups. |
static
Map<Thread, StackTraceElement[]>
|
getAllStackTraces()
Returns a map of stack traces for all live threads. |
ClassLoader
|
getContextClassLoader()
Returns the context ClassLoader for this Thread. |
static
Thread.UncaughtExceptionHandler
|
getDefaultUncaughtExceptionHandler()
Returns the default handler invoked when a thread abruptly terminates due to an uncaught exception. |
long
|
getId()
Returns the identifier of this Thread. |
final
String
|
getName()
Returns this thread's name. |
final
int
|
getPriority()
Returns this thread's priority. |
StackTraceElement[]
|
getStackTrace()
Returns an array of stack trace elements representing the stack dump of this thread. |
Thread.State
|
getState()
Returns the state of this thread. |
final
ThreadGroup
|
getThreadGroup()
Returns the thread group to which this thread belongs. |
Thread.UncaughtExceptionHandler
|
getUncaughtExceptionHandler()
Returns the handler invoked when this thread abruptly terminates due to an uncaught exception. |
static
boolean
|
holdsLock(Object obj)
Returns true if and only if the current thread holds the monitor lock on the specified object. |
void
|
interrupt()
Interrupts this thread. |
static
boolean
|
interrupted()
Tests whether the current thread has been interrupted. |
final
boolean
|
isAlive()
Tests if this thread is alive. |
final
boolean
|
isDaemon()
Tests if this thread is a daemon thread. |
boolean
|
isInterrupted()
Tests whether this thread has been interrupted. |
final
void
|
join()
Waits for this thread to die. |
final
void
|
join(long millis)
Waits at most |
final
void
|
join(long millis, int nanos)
Waits at most |
final
void
|
resume()
This method was deprecated
in API level 1.
This method exists solely for use with |
void
|
run()
If this thread was constructed using a separate
|
void
|
setContextClassLoader(ClassLoader cl)
Sets the context ClassLoader for this Thread. |
final
void
|
setDaemon(boolean on)
Marks this thread as either a daemon thread or a user thread. |
static
void
|
setDefaultUncaughtExceptionHandler(Thread.UncaughtExceptionHandler eh)
Set the default handler invoked when a thread abruptly terminates due to an uncaught exception, and no other handler has been defined for that thread. |
final
void
|
setName(String name)
Changes the name of this thread to be equal to the argument
|
final
void
|
setPriority(int newPriority)
Changes the priority of this thread. |
void
|
setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler eh)
Set the handler invoked when this thread abruptly terminates due to an uncaught exception. |
static
void
|
sleep(long millis, int nanos)
Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds plus the specified number of nanoseconds, subject to the precision and accuracy of system timers and schedulers. |
static
void
|
sleep(long millis)
Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds, subject to the precision and accuracy of system timers and schedulers. |
void
|
start()
Causes this thread to begin execution; the Java Virtual Machine
calls the |
final
void
|
stop()
This method was deprecated
in API level 1.
This method is inherently unsafe. Stopping a thread with
Thread.stop causes it to unlock all of the monitors that it
has locked (as a natural consequence of the unchecked
|
final
void
|
stop(Throwable obj)
This method was deprecated
in API level 1.
This method is inherently unsafe. See |
final
void
|
suspend()
This method was deprecated
in API level 1.
This method has been deprecated, as it is
inherently deadlock-prone. If the target thread holds a lock on the
monitor protecting a critical system resource when it is suspended, no
thread can access this resource until the target thread is resumed. If
the thread that would resume the target thread attempts to lock this
monitor prior to calling |
String
|
toString()
Returns a string representation of this thread, including the thread's name, priority, and thread group. |
static
void
|
yield()
A hint to the scheduler that the current thread is willing to yield its current use of a processor. |
Protected methods | |
|---|---|
Object
|
clone()
Throws CloneNotSupportedException as a Thread can not be meaningfully cloned. |
Inherited methods | |
|---|---|
From
class
java.lang.Object
| |
From
interface
java.lang.Runnable
| |
int MAX_PRIORITY
The maximum priority that a thread can have.
Constant Value: 10 (0x0000000a)
int MIN_PRIORITY
The minimum priority that a thread can have.
Constant Value: 1 (0x00000001)
int NORM_PRIORITY
The default priority that is assigned to a thread.
Constant Value: 5 (0x00000005)
Thread ()
Allocates a new Thread object. This constructor has the same
effect as Thread
(null, null, gname), where gname is a newly generated
name. Automatically generated names are of the form
"Thread-"+n, where n is an integer.
Thread (Runnable target)
Allocates a new Thread object. This constructor has the same
effect as Thread
(null, target, gname), where gname is a newly generated
name. Automatically generated names are of the form
"Thread-"+n, where n is an integer.
| Parameters | |
|---|---|
target |
Runnable:
the object whose run method is invoked when this thread
is started. If null, this classes run method does
nothing.
|
Thread (ThreadGroup group, Runnable target)
Allocates a new Thread object. This constructor has the same
effect as Thread
(group, target, gname) ,where gname is a newly generated
name. Automatically generated names are of the form
"Thread-"+n, where n is an integer.
| Parameters | |
|---|---|
group |
ThreadGroup:
the thread group. If null and there is a security
manager, the group is determined by SecurityManager.getThreadGroup().
If there is not a security manager or SecurityManager.getThreadGroup() returns null, the group
is set to the current thread's thread group. |
target |
Runnable:
the object whose run method is invoked when this thread
is started. If null, this thread's run method is invoked. |
| Throws | |
|---|---|
SecurityException |
if the current thread cannot create a thread in the specified thread group |
Thread (String name)
Allocates a new Thread object. This constructor has the same
effect as Thread
(null, null, name).
| Parameters | |
|---|---|
name |
String:
the name of the new thread
|
Thread (ThreadGroup group, String name)
Allocates a new Thread object. This constructor has the same
effect as Thread
(group, null, name).
| Parameters | |
|---|---|
group |
ThreadGroup:
the thread group. If null and there is a security
manager, the group is determined by SecurityManager.getThreadGroup().
If there is not a security manager or SecurityManager.getThreadGroup() returns null, the group
is set to the current thread's thread group. |
name |
String:
the name of the new thread |
| Throws | |
|---|---|
SecurityException |
if the current thread cannot create a thread in the specified thread group |
Thread (Runnable target, String name)
Allocates a new Thread object. This constructor has the same
effect as Thread
(null, target, name).
| Parameters | |
|---|---|
target |
Runnable:
the object whose run method is invoked when this thread
is started. If null, this thread's run method is invoked. |
name |
String:
the name of the new thread
|
Thread (ThreadGroup group, Runnable target, String name)
Allocates a new Thread object so that it has target
as its run object, has the specified name as its name,
and belongs to the thread group referred to by group.
If there is a security manager, its
checkAccess
method is invoked with the ThreadGroup as its argument.
In addition, its checkPermission method is invoked with
the RuntimePermission("enableContextClassLoaderOverride")
permission when invoked directly or indirectly by the constructor
of a subclass which overrides the getContextClassLoader
or setContextClassLoader methods.
The priority of the newly created thread is set equal to the priority of the thread creating it, that is, the currently running thread. The method setPriority may be used to change the priority to a new value.
The newly created thread is initially marked as being a daemon thread if and only if the thread creating it is currently marked as a daemon thread. The method setDaemon may be used to change whether or not a thread is a daemon.
| Parameters | |
|---|---|
group |
ThreadGroup:
the thread group. If null and there is a security
manager, the group is determined by SecurityManager.getThreadGroup().
If there is not a security manager or SecurityManager.getThreadGroup() returns null, the group
is set to the current thread's thread group. |
target |
Runnable:
the object whose run method is invoked when this thread
is started. If null, this thread's run method is invoked. |
name |
String:
the name of the new thread |
| Throws | |
|---|---|
SecurityException |
if the current thread cannot create a thread in the specified thread group or cannot override the context class loader methods. |
Thread (ThreadGroup group, Runnable target, String name, long stackSize)
Allocates a new Thread object so that it has target
as its run object, has the specified name as its name,
and belongs to the thread group referred to by group, and has
the specified stack size.
This constructor is identical to Thread(ThreadGroup, Runnable, String) with the exception of the fact
that it allows the thread stack size to be specified. The stack size
is the approximate number of bytes of address space that the virtual
machine is to allocate for this thread's stack. The effect of the
stackSize parameter, if any, is highly platform dependent.
On some platforms, specifying a higher value for the
stackSize parameter may allow a thread to achieve greater
recursion depth before throwing a StackOverflowError.
Similarly, specifying a lower value may allow a greater number of
threads to exist concurrently without throwing an OutOfMemoryError (or other internal error). The details of
the relationship between the value of the stackSize parameter
and the maximum recursion depth and concurrency level are
platform-dependent. On some platforms, the value of the
stackSize parameter may have no effect whatsoever.
The virtual machine is free to treat the stackSize
parameter as a suggestion. If the specified value is unreasonably low
for the platform, the virtual machine may instead use some
platform-specific minimum value; if the specified value is unreasonably
high, the virtual machine may instead use some platform-specific
maximum. Likewise, the virtual machine is free to round the specified
value up or down as it sees fit (or to ignore it completely).
Specifying a value of zero for the stackSize parameter will
cause this constructor to behave exactly like the
Thread(ThreadGroup, Runnable, String) constructor.
Due to the platform-dependent nature of the behavior of this constructor, extreme care should be exercised in its use. The thread stack size necessary to perform a given computation will likely vary from one JRE implementation to another. In light of this variation, careful tuning of the stack size parameter may be required, and the tuning may need to be repeated for each JRE implementation on which an application is to run.
Implementation note: Java platform implementers are encouraged to
document their implementation's behavior with respect to the
stackSize parameter.
| Parameters | |
|---|---|
group |
ThreadGroup:
the thread group. If null and there is a security
manager, the group is determined by SecurityManager.getThreadGroup().
If there is not a security manager or SecurityManager.getThreadGroup() returns null, the group
is set to the current thread's thread group. |
target |
Runnable:
the object whose run method is invoked when this thread
is started. If null, this thread's run method is invoked. |
name |
String:
the name of the new thread |
stackSize |
long:
the desired stack size for the new thread, or zero to indicate
that this parameter is to be ignored. |
| Throws | |
|---|---|
SecurityException |
if the current thread cannot create a thread in the specified thread group |
int activeCount ()
Returns an estimate of the number of active threads in the current thread's thread group and its subgroups. Recursively iterates over all subgroups in the current thread's thread group.
The value returned is only an estimate because the number of threads may change dynamically while this method traverses internal data structures, and might be affected by the presence of certain system threads. This method is intended primarily for debugging and monitoring purposes.
| Returns | |
|---|---|
int |
an estimate of the number of active threads in the current thread's thread group and in any other thread group that has the current thread's thread group as an ancestor |
void checkAccess ()
Determines if the currently running thread has permission to modify this thread.
If there is a security manager, its checkAccess method
is called with this thread as its argument. This may result in
throwing a SecurityException.
| Throws | |
|---|---|
SecurityException |
if the current thread is not allowed to access this thread. |
See also:
int countStackFrames ()
This method was deprecated
in API level 1.
The definition of this call depends on suspend(),
which is deprecated. Further, the results of this call
were never well-defined.
Counts the number of stack frames in this thread. The thread must be suspended.
| Returns | |
|---|---|
int |
the number of stack frames in this thread. |
| Throws | |
|---|---|
IllegalThreadStateException |
if this thread is not suspended. |
Thread currentThread ()
Returns a reference to the currently executing thread object.
| Returns | |
|---|---|
Thread |
the currently executing thread. |
void destroy ()
This method was deprecated
in API level 1.
This method was originally designed to destroy this
thread without any cleanup. Any monitors it held would have
remained locked. However, the method was never implemented.
If if were to be implemented, it would be deadlock-prone in
much the manner of suspend(). If the target thread held
a lock protecting a critical system resource when it was
destroyed, no thread could ever access this resource again.
If another thread ever attempted to lock this resource, deadlock
would result. Such deadlocks typically manifest themselves as
"frozen" processes. For more information, see
Why are Thread.stop, Thread.suspend and Thread.resume Deprecated?.
Throws UnsupportedOperationException.
| Throws | |
|---|---|
UnsupportedOperationException |
always |
void dumpStack ()
Prints a stack trace of the current thread to the standard error stream. This method is used only for debugging.
See also:
int enumerate (Thread[] tarray)
Copies into the specified array every active thread in the current
thread's thread group and its subgroups. This method simply
invokes the enumerate(Thread[])
method of the current thread's thread group.
An application might use the activeCount
method to get an estimate of how big the array should be, however
if the array is too short to hold all the threads, the extra threads
are silently ignored. If it is critical to obtain every active
thread in the current thread's thread group and its subgroups, the
invoker should verify that the returned int value is strictly less
than the length of tarray.
Due to the inherent race condition in this method, it is recommended that the method only be used for debugging and monitoring purposes.
| Parameters | |
|---|---|
tarray |
Thread:
an array into which to put the list of threads |
| Returns | |
|---|---|
int |
the number of threads put into the array |
| Throws | |
|---|---|
SecurityException |
if checkAccess() determines that
the current thread cannot access its thread group
|
Map<Thread, StackTraceElement[]> getAllStackTraces ()
Returns a map of stack traces for all live threads.
The map keys are threads and each map value is an array of
StackTraceElement that represents the stack dump
of the corresponding Thread.
The returned stack traces are in the format specified for
the getStackTrace method.
The threads may be executing while this method is called. The stack trace of each thread only represents a snapshot and each stack trace may be obtained at different time. A zero-length array will be returned in the map value if the virtual machine has no stack trace information about a thread.
If there is a security manager, then the security manager's checkPermission method is called with a RuntimePermission("getStackTrace") permission as well as RuntimePermission("modifyThreadGroup") permission to see if it is ok to get the stack trace of all threads.
| Returns | |
|---|---|
Map<Thread, StackTraceElement[]> |
a Map from Thread to an array of StackTraceElement that represents the stack trace of the corresponding thread. |
| Throws | |
|---|---|
SecurityException |
if a security manager exists and its checkPermission method doesn't allow getting the stack trace of thread. |
ClassLoader getContextClassLoader ()
Returns the context ClassLoader for this Thread. The context ClassLoader is provided by the creator of the thread for use by code running in this thread when loading classes and resources. If not set, the default is the ClassLoader context of the parent Thread. The context ClassLoader of the primordial thread is typically set to the class loader used to load the application.
If a security manager is present, and the invoker's class loader is not
null and is not the same as or an ancestor of the context class
loader, then this method invokes the security manager's checkPermission
method with a RuntimePermission("getClassLoader") permission to verify that retrieval of the context
class loader is permitted.
| Returns | |
|---|---|
ClassLoader |
the context ClassLoader for this Thread, or null
indicating the system class loader (or, failing that, the
bootstrap class loader) |
| Throws | |
|---|---|
SecurityException |
if the current thread cannot get the context ClassLoader |
Thread.UncaughtExceptionHandler getDefaultUncaughtExceptionHandler ()
Returns the default handler invoked when a thread abruptly terminates due to an uncaught exception. If the returned value is null, there is no default.
| Returns | |
|---|---|
Thread.UncaughtExceptionHandler |
|
long getId ()
Returns the identifier of this Thread. The thread ID is a positive long number generated when this thread was created. The thread ID is unique and remains unchanged during its lifetime. When a thread is terminated, this thread ID may be reused.
| Returns | |
|---|---|
long |
this thread's ID. |
String getName ()
Returns this thread's name.
| Returns | |
|---|---|
String |
this thread's name. |
See also:
int getPriority ()
Returns this thread's priority.
| Returns | |
|---|---|
int |
this thread's priority. |
See also:
StackTraceElement[] getStackTrace ()
Returns an array of stack trace elements representing the stack dump of this thread. This method will return a zero-length array if this thread has not started, has started but has not yet been scheduled to run by the system, or has terminated. If the returned array is of non-zero length then the first element of the array represents the top of the stack, which is the most recent method invocation in the sequence. The last element of the array represents the bottom of the stack, which is the least recent method invocation in the sequence.
If there is a security manager, and this thread is not the current thread, then the security manager's checkPermission method is called with a RuntimePermission("getStackTrace") permission to see if it's ok to get the stack trace.
Some virtual machines may, under some circumstances, omit one or more stack frames from the stack trace. In the extreme case, a virtual machine that has no stack trace information concerning this thread is permitted to return a zero-length array from this method.
| Returns | |
|---|---|
StackTraceElement[] |
an array of StackTraceElement, each represents one stack frame. |
| Throws | |
|---|---|
SecurityException |
if a security manager exists and its checkPermission method doesn't allow getting the stack trace of thread. |
Thread.State getState ()
Returns the state of this thread. This method is designed for use in monitoring of the system state, not for synchronization control.
| Returns | |
|---|---|
Thread.State |
this thread's state. |
ThreadGroup getThreadGroup ()
Returns the thread group to which this thread belongs. This method returns null if this thread has died (been stopped).
| Returns | |
|---|---|
ThreadGroup |
this thread's thread group. |
Thread.UncaughtExceptionHandler getUncaughtExceptionHandler ()
Returns the handler invoked when this thread abruptly terminates due to an uncaught exception. If this thread has not had an uncaught exception handler explicitly set then this thread's ThreadGroup object is returned, unless this thread has terminated, in which case null is returned.
| Returns | |
|---|---|
Thread.UncaughtExceptionHandler |
|
boolean holdsLock (Object obj)
Returns true if and only if the current thread holds the monitor lock on the specified object.
This method is designed to allow a program to assert that the current thread already holds a specified lock:
assert Thread.holdsLock(obj);
| Parameters | |
|---|---|
obj |
Object:
the object on which to test lock ownership |
| Returns | |
|---|---|
boolean |
true if the current thread holds the monitor lock on the specified object. |
| Throws | |
|---|---|
NullPointerException |
if obj is null |
void interrupt ()
Interrupts this thread.
Unless the current thread is interrupting itself, which is
always permitted, the checkAccess method
of this thread is invoked, which may cause a SecurityException to be thrown.
If this thread is blocked in an invocation of the wait(), wait(long), or wait(long, int) methods of the Object
class, or of the join(), join(long), join(long, int), sleep(long), or sleep(long, int),
methods of this class, then its interrupt status will be cleared and it
will receive an InterruptedException.
If this thread is blocked in an I/O operation upon an interruptible
channel then the channel will be closed, the thread's interrupt
status will be set, and the thread will receive a ClosedByInterruptException.
If this thread is blocked in a Selector
then the thread's interrupt status will be set and it will return
immediately from the selection operation, possibly with a non-zero
value, just as if the selector's wakeup method were invoked.
If none of the previous conditions hold then this thread's interrupt status will be set.
Interrupting a thread that is not alive need not have any effect.
| Throws | |
|---|---|
SecurityException |
if the current thread cannot modify this thread |
boolean interrupted ()
Tests whether the current thread has been interrupted. The interrupted status of the thread is cleared by this method. In other words, if this method were to be called twice in succession, the second call would return false (unless the current thread were interrupted again, after the first call had cleared its interrupted status and before the second call had examined it).
A thread interruption ignored because a thread was not alive at the time of the interrupt will be reflected by this method returning false.
| Returns | |
|---|---|
boolean |
true if the current thread has been interrupted;
false otherwise. |
See also:
boolean isAlive ()
Tests if this thread is alive. A thread is alive if it has been started and has not yet died.
| Returns | |
|---|---|
boolean |
true if this thread is alive;
false otherwise.
|
boolean isDaemon ()
Tests if this thread is a daemon thread.
| Returns | |
|---|---|
boolean |
true if this thread is a daemon thread;
false otherwise. |
See also:
boolean isInterrupted ()
Tests whether this thread has been interrupted. The interrupted status of the thread is unaffected by this method.
A thread interruption ignored because a thread was not alive at the time of the interrupt will be reflected by this method returning false.
| Returns | |
|---|---|
boolean |
true if this thread has been interrupted;
false otherwise. |
See also:
void join ()
Waits for this thread to die.
An invocation of this method behaves in exactly the same way as the invocation
join(0)
| Throws | |
|---|---|
InterruptedException |
if any thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown. |
void join (long millis)
Waits at most millis milliseconds for this thread to
die. A timeout of 0 means to wait forever.
This implementation uses a loop of this.wait calls
conditioned on this.isAlive. As a thread terminates the
this.notifyAll method is invoked. It is recommended that
applications not use wait, notify, or
notifyAll on Thread instances.
| Parameters | |
|---|---|
millis |
long:
the time to wait in milliseconds |
| Throws | |
|---|---|
IllegalArgumentException |
if the value of millis is negative |
InterruptedException |
if any thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown. |
void join (long millis,
int nanos)
Waits at most millis milliseconds plus
nanos nanoseconds for this thread to die.
This implementation uses a loop of this.wait calls
conditioned on this.isAlive. As a thread terminates the
this.notifyAll method is invoked. It is recommended that
applications not use wait, notify, or
notifyAll on Thread instances.
| Parameters | |
|---|---|
millis |
long:
the time to wait in milliseconds |
nanos |
int:
0-999999 additional nanoseconds to wait |
| Throws | |
|---|---|
IllegalArgumentException |
if the value of millis is negative, or the value
of nanos is not in the range 0-999999 |
InterruptedException |
if any thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown. |
void resume ()
This method was deprecated
in API level 1.
This method exists solely for use with suspend(),
which has been deprecated because it is deadlock-prone.
For more information, see
Why
are Thread.stop, Thread.suspend and Thread.resume Deprecated?.
Resumes a suspended thread.
First, the checkAccess method of this thread is called
with no arguments. This may result in throwing a
SecurityException (in the current thread).
If the thread is alive but suspended, it is resumed and is permitted to make progress in its execution.
| Throws | |
|---|---|
SecurityException |
if the current thread cannot modify this thread. |
See also:
void run ()
If this thread was constructed using a separate
Runnable run object, then that
Runnable object's run method is called;
otherwise, this method does nothing and returns.
Subclasses of Thread should override this method.
void setContextClassLoader (ClassLoader cl)
Sets the context ClassLoader for this Thread. The context
ClassLoader can be set when a thread is created, and allows
the creator of the thread to provide the appropriate class loader,
through getContextClassLoader, to code running in the thread
when loading classes and resources.
If a security manager is present, its checkPermission
method is invoked with a RuntimePermission("setContextClassLoader") permission to see if setting the context
ClassLoader is permitted.
| Parameters | |
|---|---|
cl |
ClassLoader:
the context ClassLoader for this Thread, or null indicating the
system class loader (or, failing that, the bootstrap class loader) |
| Throws | |
|---|---|
SecurityException |
if the current thread cannot set the context ClassLoader |
void setDaemon (boolean on)
Marks this thread as either a daemon thread or a user thread. The Java Virtual Machine exits when the only threads running are all daemon threads.
This method must be invoked before the thread is started.
| Parameters | |
|---|---|
on |
boolean:
if true, marks this thread as a daemon thread |
| Throws | |
|---|---|
IllegalThreadStateException |
if this thread is alive |
SecurityException |
if checkAccess() determines that the current
thread cannot modify this thread
|
void setDefaultUncaughtExceptionHandler (Thread.UncaughtExceptionHandler eh)
Set the default handler invoked when a thread abruptly terminates due to an uncaught exception, and no other handler has been defined for that thread.
Uncaught exception handling is controlled first by the thread, then
by the thread's ThreadGroup object and finally by the default
uncaught exception handler. If the thread does not have an explicit
uncaught exception handler set, and the thread's thread group
(including parent thread groups) does not specialize its
uncaughtException method, then the default handler's
uncaughtException method will be invoked.
By setting the default uncaught exception handler, an application can change the way in which uncaught exceptions are handled (such as logging to a specific device, or file) for those threads that would already accept whatever "default" behavior the system provided.
Note that the default uncaught exception handler should not usually defer to the thread's ThreadGroup object, as that could cause infinite recursion.
| Parameters | |
|---|---|
eh |
Thread.UncaughtExceptionHandler:
the object to use as the default uncaught exception handler.
If null then there is no default handler. |
| Throws | |
|---|---|
SecurityException |
if a security manager is present and it
denies RuntimePermission
("setDefaultUncaughtExceptionHandler") |
void setName (String name)
Changes the name of this thread to be equal to the argument
name.
First the checkAccess method of this thread is called
with no arguments. This may result in throwing a
SecurityException.
| Parameters | |
|---|---|
name |
String:
the new name for this thread. |
| Throws | |
|---|---|
SecurityException |
if the current thread cannot modify this thread. |
See also:
void setPriority (int newPriority)
Changes the priority of this thread.
First the checkAccess method of this thread is called
with no arguments. This may result in throwing a
SecurityException.
Otherwise, the priority of this thread is set to the smaller of
the specified newPriority and the maximum permitted
priority of the thread's thread group.
| Parameters | |
|---|---|
newPriority |
int:
priority to set this thread to |
| Throws | |
|---|---|
IllegalArgumentException |
If the priority is not in the
range MIN_PRIORITY to
MAX_PRIORITY. |
SecurityException |
if the current thread cannot modify this thread. |
void setUncaughtExceptionHandler (Thread.UncaughtExceptionHandler eh)
Set the handler invoked when this thread abruptly terminates due to an uncaught exception.
A thread can take full control of how it responds to uncaught exceptions by having its uncaught exception handler explicitly set. If no such handler is set then the thread's ThreadGroup object acts as its handler.
| Parameters | |
|---|---|
eh |
Thread.UncaughtExceptionHandler:
the object to use as this thread's uncaught exception
handler. If null then this thread has no explicit handler. |
| Throws | |
|---|---|
SecurityException |
if the current thread is not allowed to modify this thread. |
void sleep (long millis,
int nanos)
Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds plus the specified number of nanoseconds, subject to the precision and accuracy of system timers and schedulers. The thread does not lose ownership of any monitors.
| Parameters | |
|---|---|
millis |
long:
the length of time to sleep in milliseconds |
nanos |
int:
0-999999 additional nanoseconds to sleep |
| Throws | |
|---|---|
IllegalArgumentException |
if the value of millis is negative, or the value of
nanos is not in the range 0-999999 |
InterruptedException |
if any thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown. |
void sleep (long millis)
Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds, subject to the precision and accuracy of system timers and schedulers. The thread does not lose ownership of any monitors.
| Parameters | |
|---|---|
millis |
long:
the length of time to sleep in milliseconds |
| Throws | |
|---|---|
IllegalArgumentException |
if the value of millis is negative |
InterruptedException |
if any thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown. |
void start ()
Causes this thread to begin execution; the Java Virtual Machine
calls the run method of this thread.
The result is that two threads are running concurrently: the
current thread (which returns from the call to the
start method) and the other thread (which executes its
run method).
It is never legal to start a thread more than once. In particular, a thread may not be restarted once it has completed execution.
| Throws | |
|---|---|
IllegalThreadStateException |
if the thread was already started. |
void stop ()
This method was deprecated
in API level 1.
This method is inherently unsafe. Stopping a thread with
Thread.stop causes it to unlock all of the monitors that it
has locked (as a natural consequence of the unchecked
ThreadDeath exception propagating up the stack). If
any of the objects previously protected by these monitors were in
an inconsistent state, the damaged objects become visible to
other threads, potentially resulting in arbitrary behavior. Many
uses of stop should be replaced by code that simply
modifies some variable to indicate that the target thread should
stop running. The target thread should check this variable
regularly, and return from its run method in an orderly fashion
if the variable indicates that it is to stop running. If the
target thread waits for long periods (on a condition variable,
for example), the interrupt method should be used to
interrupt the wait.
For more information, see
Why
are Thread.stop, Thread.suspend and Thread.resume Deprecated?.
Forces the thread to stop executing.
If there is a security manager installed, its checkAccess
method is called with this
as its argument. This may result in a
SecurityException being raised (in the current thread).
If this thread is different from the current thread (that is, the current
thread is trying to stop a thread other than itself), the
security manager's checkPermission method (with a
RuntimePermission("stopThread") argument) is called in
addition.
Again, this may result in throwing a
SecurityException (in the current thread).
The thread represented by this thread is forced to stop whatever
it is doing abnormally and to throw a newly created
ThreadDeath object as an exception.
It is permitted to stop a thread that has not yet been started. If the thread is eventually started, it immediately terminates.
An application should not normally try to catch
ThreadDeath unless it must do some extraordinary
cleanup operation (note that the throwing of
ThreadDeath causes finally clauses of
try statements to be executed before the thread
officially dies). If a catch clause catches a
ThreadDeath object, it is important to rethrow the
object so that the thread actually dies.
The top-level error handler that reacts to otherwise uncaught
exceptions does not print out a message or otherwise notify the
application if the uncaught exception is an instance of
ThreadDeath.
| Throws | |
|---|---|
SecurityException |
if the current thread cannot modify this thread. |
void stop (Throwable obj)
This method was deprecated
in API level 1.
This method is inherently unsafe. See stop()
for details. An additional danger of this
method is that it may be used to generate exceptions that the
target thread is unprepared to handle (including checked
exceptions that the thread could not possibly throw, were it
not for this method).
For more information, see
Why
are Thread.stop, Thread.suspend and Thread.resume Deprecated?.
Forces the thread to stop executing.
If there is a security manager installed, the checkAccess
method of this thread is called, which may result in a
SecurityException being raised (in the current thread).
If this thread is different from the current thread (that is, the current
thread is trying to stop a thread other than itself) or
obj is not an instance of ThreadDeath, the
security manager's checkPermission method (with the
RuntimePermission("stopThread") argument) is called in
addition.
Again, this may result in throwing a
SecurityException (in the current thread).
If the argument obj is null, a
NullPointerException is thrown (in the current thread).
The thread represented by this thread is forced to stop
whatever it is doing abnormally and to throw the
Throwable object obj as an exception. This
is an unusual action to take; normally, the stop method
that takes no arguments should be used.
It is permitted to stop a thread that has not yet been started. If the thread is eventually started, it immediately terminates.
| Parameters | |
|---|---|
obj |
Throwable:
the Throwable object to be thrown. |
| Throws | |
|---|---|
SecurityException |
if the current thread cannot modify this thread. |
NullPointerException |
if obj is null. |
void suspend ()
This method was deprecated
in API level 1.
This method has been deprecated, as it is
inherently deadlock-prone. If the target thread holds a lock on the
monitor protecting a critical system resource when it is suspended, no
thread can access this resource until the target thread is resumed. If
the thread that would resume the target thread attempts to lock this
monitor prior to calling resume, deadlock results. Such
deadlocks typically manifest themselves as "frozen" processes.
For more information, see
Why
are Thread.stop, Thread.suspend and Thread.resume Deprecated?.
Suspends this thread.
First, the checkAccess method of this thread is called
with no arguments. This may result in throwing a
SecurityException (in the current thread).
If the thread is alive, it is suspended and makes no further progress unless and until it is resumed.
| Throws | |
|---|---|
SecurityException |
if the current thread cannot modify this thread. |
See also:
String toString ()
Returns a string representation of this thread, including the thread's name, priority, and thread group.
| Returns | |
|---|---|
String |
a string representation of this thread. |
void yield ()
A hint to the scheduler that the current thread is willing to yield its current use of a processor. The scheduler is free to ignore this hint.
Yield is a heuristic attempt to improve relative progression between threads that would otherwise over-utilise a CPU. Its use should be combined with detailed profiling and benchmarking to ensure that it actually has the desired effect.
It is rarely appropriate to use this method. It may be useful
for debugging or testing purposes, where it may help to reproduce
bugs due to race conditions. It may also be useful when designing
concurrency control constructs such as the ones in the
java.util.concurrent.locks package.
Object clone ()
Throws CloneNotSupportedException as a Thread can not be meaningfully cloned. Construct a new Thread instead.
| Returns | |
|---|---|
Object |
a clone of this instance. |
| Throws | |
|---|---|
CloneNotSupportedException |
always |